package com.wly.utils;



import io.jsonwebtoken.Claims;
import io.jsonwebtoken.JwtBuilder;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;

import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.util.Base64;
import java.util.Date;
import java.util.UUID;

/*
* JWT工具类
* */
public class JwtUtil {
    // 有效期为
    public static final Long JWT_TTL = 60 * 60 * 24*1000L;// 60*60*1000 一小时
    // 设置秘钥说明文
    public static final String JWT_KEY = "wly";

    public static String getUUID(){
        return UUID.randomUUID().toString().replaceAll("-","");
    }

    /**
    * 生成JWT
    * @Param subject token中要存放的数据(Json格式)
    * @Param ttlMillis token超时时间
    * */
    public static String createJWT(String subject){
        JwtBuilder builder = getJwtBuilder(subject,null,getUUID());// 设置过期时间
        return builder.compact();
    }

    public static String createJWT(String subject,Long ttlMillis){
        JwtBuilder builder = getJwtBuilder(subject,ttlMillis,getUUID());// 设置过期时间
        return builder.compact();
    }

    private static JwtBuilder getJwtBuilder(String subject,Long ttlMillis,String uuid){
        SignatureAlgorithm signatureAlgorithm = SignatureAlgorithm.HS256;
        SecretKey secretKey = generalKey();
        long nowMillis = System.currentTimeMillis();
        Date now = new Date(nowMillis);
        if (ttlMillis == null){
            ttlMillis = JwtUtil.JWT_TTL;
        }
        long expMillis = nowMillis + ttlMillis;
        Date expDate = new Date(expMillis);
        return Jwts.builder()
                .setId(uuid) // 唯一的ID
                .setSubject(subject) //主题 可以是JSON数据
                .setIssuer("ly") // 签发者
                .setIssuedAt(now) // 签发时间
                .signWith(signatureAlgorithm,secretKey) // 使用HS256对称加密算法签名，第二个参数为秘钥
                .setExpiration(expDate);
    }
    /*
    * 创建Token
    * */
    public static String createJWT(String id,String subject,Long ttlMillis){
        JwtBuilder builder = getJwtBuilder(subject,ttlMillis,id);// 设置过期时间
        return builder.compact();
    }

    public static void main(String[] args) throws Exception {
        String jwt = createJWT("456");
        Claims claims = parseJWT(jwt);
        String id = claims.getSubject();
        System.out.println(id);
        System.out.println(claims);
    }

    /**
     * 生成加密后的秘钥 secretKey
     * @return
     */
    public static SecretKey generalKey() {
        byte[] encodedKey = Base64.getDecoder().decode(JwtUtil.JWT_KEY);
        SecretKey key = new SecretKeySpec(encodedKey, 0, encodedKey.length, "AES");
        return key;
    }

    /**
     * 解析
     *
     * @param jwt
     * @return
     * @throws Exception
     */
    public static Claims parseJWT(String jwt) throws Exception {
        SecretKey secretKey = generalKey();
        return Jwts.parser()
                .setSigningKey(secretKey)
                .parseClaimsJws(jwt)
                .getBody();
    }
}
